This application is based on Japanese Application No. 22028 filed on Jan. 29, 1999, and Japanese Application No. 94634 filed on Apr. 1, 1999 in Japan, the contents of which are incorporated hereinto by reference.
This invention relates to a high current power source used primarily to power a drive motor for automobiles such as hybrid and electric automobiles.
A high current power source used to power an automobile drive motor achieves high output voltage by connecting power modules in series. This is for the purpose of increasing drive motor output. In a power source used for this type of application, an extremely high current passes through batteries. For example, in hybrid automobiles, an extremely high current passes through batteries when staring and accelerating. This is because the automobiles are accelerated by the output of the batteries. In addition, high current also passes through batteries when rapidly charging in a short time.
The high current power source requires compulsory cooling when the temperature of the batteries rises. In a power source in which a plurality of rows of power modules arranged in a lateral fashion are housed in a holder-case, it is important to cool each power module equally. If a difference in temperature is produced in the batteries, high temperature batteries will easily deteriorate in efficiency.
For example, the structure for housing a plurality of power modules in a holder-case and cooling each power module equally is described in Japanese Non-examined Patent Publication HEI 10-270095 (1998). As shown in the cross-section view of FIG. 1, a holder-case 102 described in the Publication is provided with an air-inlet 1035 in the lower part and an air-outlet 1036 in the upper part, and allows cooling of power modules 101 by letting air flow from the air-inlet 1035 in the lower part into the air-outlet 1036 in the upper part. Cooling adjustment fins 1047 are provided within the holder-case 102 to adjust the air speed flowing on the surface of the power modules 101.
A holder-case with this structure makes the air speed flowing on the surface of power modules provided in the upper part higher than the air speed flowing on the surface of power modules provided in the lower part. If the air speeds flowing on the surfaces of the upper and lower power modules are the same, the lower power modules are cooled more effectively than the upper power modules since the temperature of air flowing on the surface of the lower power modules is lower than the temperature of air flowing on the surface of the upper power modules, and thereby the difference in temperature is produced.
Gaps between cooling adjustment fins and power modules are formed to be gradually narrower toward the upper part to make the air speed flowing on the surface of power modules in the upper part higher than the air speed flowing in the lower part. This is because air speed becomes higher when gaps are formed to be narrower.
A power source with this structure can cool the upper and lower power modules because the lower power modules are cooled by low temperature air and the upper modules are cooled by rapid flowing air. However, in this structure, it is extremely difficult to cool the upper and lower power modules under the same conditions. This is because cooling-air temperature of lower power modules is low and cooling-air temperature of the upper power modules is high. Even if the air speed flowing on the surface of upper power modules is increased, it is difficult to cool the upper power modules efficiently, due to the high temperature air, like the lower power modules are cooled. For this reason, power modules provided near an air-inlet can be cooled efficiently, however power modules provided near an air-outlet can not be cooled efficiently. This type of power resource has the drawback that the difference in temperature is produced. Thus, the power modules provided near the air-outlet may easily deteriorate in efficiency.
The present invention was developed to resolve these types of problems with prior art power sources. Thus it is a primary object of the present invention to provide a power source that can cool all of the whole power modules housed in the holder-case equally and efficiently, and prevent batteries from deteriorating in efficiency due to the difference in temperature.
The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.
The power source of the present invention is provided with a holder-case in which a plurality of rows of slender power modules are housed in a parallel fashion. The power modules are cooled by passing air through the holder-case.
Further, the power source of the present invention is provided with a main air inlet on one end and an air-outlet on the other end. An air-duct is formed between the air-inlet and the air-outlet. The air-duct is provided with intermediate air-inlets for supplying air to the air-duct. In this power source, both the main air-inlet and intermediate air-inlets supply air to the air-duct to cool a plurality of rows of power modules housed in the holder-case.
A power source of this structure has the feature all of the power modules housed in the holder-case can be cooled equally and batteries can be prevented from deteriorating in efficiency due to the difference in temperature. The power source can cool all of the power modules equally and efficiently by both the main air-inlets and intermediate air-inlets air supply to the air-duct.
Further, in the power source of the present invention, air-outlets can be provided at both ends of a holder-case and intermediate air-inlets, which pass through the holder-case, can be provided on the way of the air-duct. By this, air flows into an air-duct disposed in the holder-case through the intermediate air-inlets. The air flowing into the air-duct compulsorily cools a plurality of power modules disposed in the air-duct.
A power source with this structure has the feature that all ofthe power modules housed in the holder-case can be cooled equally and efficiently and batteries can be prevented from deteriorating in efficiency due to by the difference in temperature. Especially, the power source with this structure can cool power modules housed in the middle of the holder-case efficiently by passing cold air through the middle part of the holder-case, which is considered to be the most difficult to cool, from the intermediate air-inlets.